This invention relates to an auxiliary air supplying apparatus for an internal combustion engine for motor vehicles or the like.
Generally, in internal combustion engines for automobiles, the idling air to gas ratio is lean when the intake throttle valve is closed, or when auxiliary apparatus such as an air conditioner or the like are operated while the engine is idling. To prevent this lean mixture from occuring in the above mentioned cases, additional devices other than the throttle valves are necessitated to supply sufficient auxiliary air to the engine.
FIG. 1 illustrates an example of such a conventional internal combustion engine which is equipped with an electronically controlled fuel injection apparatus. Such engines are set forth, e.g. in Japanese Public Disclosure No. SHO 55-57641 and Japanese Utility Model Publication No. SHO 53-52993.
In FIG. 1, the air enters through an air cleaner 1 and is supplied to an engine 2 through an intake passageway 3. A throttle chamber 4 is provided along the intake passageway 3. Throttle valves 15 and 16 are provided in the throttle chamber 4. The throttle chamber 4 also has a bypass passageway 6 formed therein for allowing air to bypass the throttle valves 15 and 16. An adjusting screw 7 is externally inserted into the bypass passageway 6 for controlling the amount of air flowing therethrough thereby controlling the rotating speed of the engine while idling. In other words, the effective cross sectional area in the bypass passageway 6 through which additional air is allowed to flow is increased or decreased depending upon the shut-off degree of the adjusting screw 7, so that an appropriate quantity of idling air is securely adjusted for.
The intake passageway 3 is further formed with another bypass passageway 8. One end of the bypass passageway 8 is conected to an upstream side of the intake passageway 3, (on the right side of the throttle valves 15 and 16 in FIG. 1.) and the other end thereof is divided into two passageways, each of which is connected along a downstream side of the intake passageway 3 (on the left side of the throttle valves 15 and 16 in FIG. 1). A pair of electro magnetic valves 9 and 10 are attached to a branch portion of the bypass passageway 8. The electro magnetic valves 9 and 10 are respectively opened when the electrical load on the engine increases (for example, when the head lights are turned ON, the air conditioner is turned ON, etc.), so that the bypass passageway 8 is communicated with the intake passageway 3 thereby allowing additional auxiliary air to flow from the upstream to the downstream side of the intake passageway 3.
In the above described construction, additional auxiliary air is supplied to the engine 2 through the bypass passageway 8 which bypasses the throttle valves 15 and 16. Consequently, additional air may be supplemented during engine idling to compensate for an increased electrical load condition. Hence, a desired idling rotating speed can be assured.
Furthermore, the intake passageway 3 is also formed with a bypass passageway 11 which also bypases the throttle chamber 4. An air regulator 13 is interposed in the bypass passageway 11 and is opened or closed in response to the temperature of engine cooling water which circulates in a hot water radiating passageway 12 formed along the intake passageway 3. While the engine is being warmed-up during cold circumstances, the above-mentioned air regulator 13 is opened to allow the bypass passageway 11 to communicate with the intake passageway 3.
Consequently, at low temperatures, the air intake during idling is increased by supplementary auxiliary air being fed through the bypass passageway 11 to the engine; therefore, the idling rotating speed increases to promote the warming-up of the engine.
The intake passageway 3 is further formed with another bypass passageway 14 having a negative pressure control valve 5 formed therein. The valve 5 is opened when the intake negative pressure exceeds a predetermined value at the time of deceleration, thereby allowing bypass auxiliary air to flow through the bypass passageway 14 from the upstream to the downstream side of the intake passageway 3. Thus, an excessive increase of intake negative pressure is compensated for and a reduction in the idling speed of the engine is thereby prevented.
As described above, a regulated amount of auxiliary air is supplied to the engine 2 by utilizing extra devices other than the throttle valves 15 and 16 in accordance with load conditions on the engine, engine temperature, negative air pressure during deceleration, etc.
Reference numeral 18 indicates a fuel injection valve which is driven and controlled by a control circuit (not shown). An air flow meter 17 is positioned in the intake passageway 3 and produces a detection signal indicative of the amount of intake air being passed therethrough. The control circuit adjusts the position of the valve 18 in response to the detection signal from the flow meter 17 thereby controlling the amount of fuel being injected into the intake passageway 3.
However, many problems exist in the construction of the above-described prior-art apparatus. Namely, the above-mentioned adjusting screw 7, electro magnetic valves 9 and 10, air regulator 13, and negative pressure control valve 5 as well as the bypass passageways 6, 8, 11 and 14 are independently connected to the intake passageway 3, and therefore, the layout of each member is complicated. Furthermore, their attachment is complicated and difficult since many air pipes are required. Consequently, smooth air flow cannot be obtained, and air is randomly supplied to the engine 2 since there are many air introducing portions.
Furthermore, many parts are required which causes the total weight of the apparatus to increase as well as requiring higher production costs.